#include <bits/stdc++.h>
#define dbg(i,j) cout<<"I am "<<i<<" = "<<endl<<j<<endl;
#define dbr(name,a) cout<<name<<endl;for(auto x:a)cout<<x<<" ";cout<<endl;
#define DBR(name,a) cout<<name<<endl;for(auto x:a){ for(auto y:x)cout<<y<<" ";cout<<endl;}
#define dbmp(name,a) cout<<name<<endl;for(auto x:a){ cout<<x.first<<"\t"<<x.second<<endl;}
#define dbp(name,a) cout<<name<<endl;cout<<a.first<<"\t"<<a.second<<endl;
#define boost ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;

typedef long long int big;

typedef  long double fig;


big power(big x, big y, big p)
{
    big res = 1;      // Initialize result

    x = x % p;  // Update x if it is more than or
                // equal to p

    while (y > 0)
    {
        // If y is odd, multiply x with result
        if (y & 1)
            res = (res*x) % p;

        // y must be even now
        y = y>>1; // y = y/2
        x = (x*x) % p;
    }
    return res;
}





int main(){
    big t=1;
    //scanf("%lld",&t);
    while(t--){
        big n;
        cin>>n;
        vector<big> arr(n);
        for(big i=0;i<n;i++){
            cin>>arr[i];
            if(arr[i]>0){
                arr[i]++;
            }
        }
        vector<big> leftc(n);
        vector<big> rightc(n);
        big c=0;
        for(big i=0;i<n;i++){
            c=c-1;
            c=max(c,arr[i]);
            rightc[i]=c;
        }
        c=0;
        for(big i=n-1;i>=0;i--){
            c=c-1;
            c=max(c,arr[i]);
            leftc[i]=c;
        }
        big count=0;
        for(big i=0;i<n-1;i++){
            if(leftc[i]==0 && rightc[i]==0){
                count++;
            }
        }
        cout<<count<<"\n";
    }
    return 0;
}

//